There are vehicles each equipped with an engine provided with a supercharger such as a turbocharger. A turbocharger generates compressed air by rotating a turbine by using exhaust gas discharged from an engine, and rotating a compressor connected coaxially with the turbine. The turbocharger increases the output efficiency of the engine by supplying the compressed air to the engine.
In the case of an engine provided with a turbocharger, there is a case where an engine control system is provided with a main ECU (Electronic Control Unit) for mainly controlling the engine, and a sub ECU for controlling the turbocharger. In the control by the main ECU and the sub ECU, for example, a control method is adopted in which the main ECU provides a boost pressure command to the sub ECU and the sub ECU controls an operation of the turbocharger such that the boost pressure is obtained. In this method, the sub ECU achieves a target boost pressure by, for example, feedback control.
As a related technique, PTL 1 discloses a technique in which in an ECU composed of a main ECU and a sub ECU which are provided with computers independent of each other, the sub ECU performs control of a control target device independently from the main ECU at the time of a failure of the main ECU, or the like.